(p11 plugin) hsm memory exhaustion issue during long performance tests

[John Vrbanac]

During long performance tests, it was discovered in heavy load use cases that not closing sessions in the p11 plugin could eventually cause memory exhaustion issues within an HSM.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/167749

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/167749
Committed: https://git.openstack.org/cgit/openstack/barbican/commit/?id=34e3c16992ac68f94d46d1214ed431a82386b866
Submitter: Jenkins
Branch: master

commit 34e3c16992ac68f94d46d1214ed431a82386b866
Author: John Vrbanac <email address hidden>
Date: Wed Mar 25 14:34:12 2015 -0500

    Switching how we handle sessions in p11_crypto

    Previously, we were trying to use pre-existing sessions and
    semaphores to deal with our concurrency issues. However, this
    led to HSM memory exhaustion due to the sessions never closing.
    To mitigate this, I'm switching to a model where we're opening
    and closing sessions as we need them. By extension, this removes
    our need for semaphores. We can explore ways of making this more
    efficient in the future, but this change should address the
    outstanding issue.

    Fixes Bug: 1436529

    Change-Id: I830f3f770a93d5d82650ec93bb8fa89e3cee5a73